The present invention relates to a frame for a vehicle which constitutes part of a vehicle body of the vehicle, such as automotive vehicles, and specifically relates to a frame for a vehicle which is formed to have a closed cross section.
A frame for a vehicle (a vehicle-body frame), such as a side sill or a pillar which constitute part of a vehicle body of the vehicle, such as automotive vehicles, is generally formed to have a closed cross section as well known. It is also known that a bead projecting toward the inside of the frame is formed at a vehicle-body frame to reinforce the vehicle-body frame.
Japanese Patent Laid-Open Publication No. 2010-137839, for example, discloses a side sill which is formed to have a closed cross section by an outer panel and an inner panel, in which a bead extending in a longitudinal direction and projecting toward the inside of the side sill is formed at the outer panel. Further, Japanese Patent Laid-Open Publication No. 2009-274658, for example, discloses another side sill formed to have the closed cross section by an outer panel and an inner panel, in which hollow protruding portions extending in a longitudinal direction and protruding toward the inside of the side sill are formed at the outer panel and the inner panel.
Herein, it has been desired that the bending strength of the vehicle-body frame, such as the side sill or the pillar, is increased so that the frame may not improperly deform toward the inside of the frame even when a load acts on the vehicle from the outside, aiming at improving the safety of passengers properly in a vehicle side collision or the like.
When the load acts on the frame formed to have the closed cross section to bend the frame, as specifically described later, a third face portion which is located between a first face portion on which a compressive force acts and a second face portion on which a tensional force acts and forms a ridgeline together with the first face portion may protrude toward the outside of the frame and have buckling, so that a bending deformation of the frame may be promoted improperly.
Herein, in a case in which the bead is formed to have a closed cross section at the frame and extend in the longitudinal direction of the frame as disclosed in the above-described patent publications, while the bending rigidity of the frame may be improved, the above-described bead may not function very well in restraining the above-described bucking of the third face portion when the load acts on the first face of the frame from the outside. Accordingly, the bead may not be necessarily sufficient as means for restraining the bending deformation of the frame, so that further improvements of the bending strength of the frame should be desired.